In breaking tire beads from wheels, prior art bead breakers generally utilize application of force in an axial plane, that is, in a plane that includes the axis of the wheel. While this method works acceptably for breaking tire beads from most types of wheels, breaking a tire bead from an all-terrain vehicle (ATV) wheel is more difficult due to certain features of ATV wheels and tires.
Balloon-like ATV tires have flexible walls that absorb much of the force applied during bead breaking with prior art devices. The flexible tire walls of ATV tires deflect through much of the range of motion of prior art bead breakers, thus absorbing most of the applied force and reducing the amount of force directed to the tire bead. In addition, ATV wheels include a safety rib adjacent to the wheel rim to retain the tire bead in place during normal tire usage. As compared with other types of wheels, breaking a tire bead from an ATV wheel takes additional force to push the tire bead over the safety rib. These two characteristics, flexible tire walls and the safety rib, together increase the difficulty of successful bead breaking utilizing many of the prior art bead breakers.
Several prior art bead breakers are directed toward ATV wheels and to overcoming the difficulty in breaking ATV tire beads. Each of these prior art bead breakers utilize application of bead-breaking force in an axial plane. Callas (U.S. Pat. No. 4,756,354), Sheets (U.S. Pat. No. 4,969,498), and Reeves (U.S. Pat. No. 5,009,257) each utilize a conventional lever-mounted design along with a specialized device intended to maintain engagement of a bead-breaking foot with a tire bead during bead breaking. Wicklund (U.S. Pat. No. 5,191,934) uses a rim-mounted device wherein a bead-breaking foot is forced downward by progression of a rigidly-mounted screw; a leading edge of the foot is offset from the rim to allow progression of the foot over an ATV safety rib.
Complete tire changing requires bead breaking followed by tire demounting and mounting on a wheel. Such complete tire changing is facilitated through use of a center-post tire changer with an included bead breaker, as exemplified in Beemer (U.S. Pat. No. 4,461,335). For reasons discussed above, however, breaking beads from ATV wheels is problematic in many such prior art devices. Moreover, rim-secured bead breakers such as the Wicklund device are not easily securable on a wheel secured to a center-post tire changer, and cannot fully exploit the ease of tool movement allowed by a center post.
While the prior art has progressed in providing devices capable of breaking ATV tire beads from wheels, there is a need for a bead breaker usable on a center-post tire changer.